Bitcoin Mempool Mismatch Between Nodes

[DaveF]

Good morning everyone,

@ o_e_l_e_o,

I appreciate your explanation and the breakdown of the quirks of the mempool / mining process.  Also I didn't realize that the inbound and outbound connections were functionally identical but it makes sense when I think about it so thank you for that comment. 

@ DaveF,

Yes my computer has more RAM than that but I'm running the blockchain on an external HD that's connected via USB 3.1.  Also I believe that I am properly sending data to the bitcoin network behind the VPN as certain gateways for our VPN provider do allow for port forwarding which I've poked a hole in my router to open.  In fact over the last 20 hours or so it appears that my node has sent over 5GB of data.  At one point I had 37 inbound connections behind the VPN (now it's down to about 1/3 of that however).

Also just an FYI I did notice that the same issue with the block propagation delay to my node (behind the VPN) happened again as I waited for another transaction I sent shortly after I posted.  This issue however seems to happen fairly regularly as this has happened several times over at least the last year or two I've been spot checking with both with my node in the clear and the one running behind the VPN connection.  Regardless though everything seems to be synched up at this point. Either way I appreciate your feedback. Curious though, how did you know what my VPN provider was?  I'm assuming you seen the IP and looked it up but how did you get the IP?  Thanks.

Didn't (and don't) know who your provider is or what your IP is, but it's a common issue with a lot of VPNs. Public IP4 IPs are expensive. With the IP4 address space exhausted $35+ per IP is common.

So it's not like they can just keep throwing new IPs into the mix. So blocks of IPs get blacklisted and then issues start to come up because even if they are doing a 1 < -> 1 IP for your VPN which most places don't, the last person on that IP could have been an ass and killed it's reputation. And as I said if it's a shared public IP like 90%+ of the providers then it's even worse. Since you don't know what other people on that IP are doing.

-Dave

[BitcoinCanSaveUsAll]

Hello fellow Bitcoiners,

I hope you're all having a good holiday season so far!  I'm replying back to try to further look into this issue with the memory mismatch between nodes and to try to dig deeper into my understanding of how bitcoin transactions propagate on the network and how they should be able to be interpreted by our nodes assuming everything is operating normally while in the mempool.  As you may recall I've been quite skeptical of how things have been operating lately since the ordinals and inscriptions were released as this is when I've noticed these memory discrepancies first arise and I've been running several nodes for years.

Either way I wanted to compare what my node sees (Windows 11 based node running version 20.2 currently with a French IP address) to what both mempool dot space and blockstream dot info sees.  With the new goggle feature recently added to mempool dot space allowing folks to quickly identify the types of transactions that are currently pending in the mempool (I'm hopeful they'll also allow this feature to explore previous blocks in the future), I've been trying to see where the discrepancies are.  With that said, I've been looking into the various types of TXNS in it's mempool, then cross checking them with with both my node's mempool vs. blockstream dot info's mempool.  Oddly enough (or what seems that way to me) is that while I've been continuing to see a huge discrepancy in my mempool memory usage on my node and pending TXNS (mines currently 580.75 MB with ~ 88457 pending TXNS vs. mempool dot spaces 316,391 TXNS and 1.51 GB as of ~ 1735 UTC today) it seems as though there are specific types of TXNS that I'm not seeing as noted below:


That said, the few below transactions were both in mempool dot space as well as in blockstream dot info's mempools had the following results in my mempool:

17:22:01
 
getrawtransaction 7d5db5b07609af7432fec8c395c3330e730f6fb9f36d8cf61cb56addeec0240f   - This was flagged as an incription TX)


17:22:01
 
No such mempool or blockchain transaction. Use gettransaction for wallet transactions. (code -5)


17:23:00
 
gettxout d71afc2f7e688798b7af5860a9730325ddec2c35db5a526f91e5fc4590d50a92 ,0 (this TXN showed up in my mempool as well as can be seen below)


17:23:00
 
{
  "bestblock": "00000000000000000002088865449c4fafb0e05d498254429b7b71cd13ffb79b",
  "confirmations": 0,
  "value": 0.37011741,
  "scriptPubKey": {
    "asm": "OP_HASH160 3354fa2425aa222086c0ac4df2e3cf38f69e27cb OP_EQUAL",
    "hex": "a9143354fa2425aa222086c0ac4df2e3cf38f69e27cb87",
    "reqSigs": 1,
    "type": "scripthash",
    "addresses": [
      "36NSBe6tr6rAYnKrj5tHnTGNLUdJ7wFd7q"
    ]
  },
  "coinbase": false
}


17:23:42
 
gettxout 01b75016c9a58675b333a38e8eaa495b5d1643bae2aefe2453dc36010dad2e40 ,0 (this was flagged in the mempool dot space as a coinjoin and only showed up after it was confirmed by the network in my node)


17:23:42
 
null

I should also likely point out my current node config file for this node is set as follows:

prune=0
txindex=1
dbcache=5000
datadir=E:\Bitcoin
assumevalid=0
peerbloomfilters=1
port=33985
maxmempool=1500
permitbaremultisig=0

That all being the case, I'm unsure why the mempool size continues on as my computer has more than adequate resources to see the full mempool.  I should also note that another of my nodes running on Windows 10 (also version 20.2) sees a similar amount of memory and TXNS that my French IP nodes sees).  That all being said, any feedback from you related to why the discrepancy in size and why there are missing transactions would be much appreciated.

I really hate to think this is some kind of attack but considering the legal and technical turmoil of late nothing would surprise me.  Thanks in advance!

[BitcoinCanSaveUsAll]

Ok, so after continuing though and checking dozens of transactions labeled as inscriptions on mempool dot space and cross checking them with my node and blockstream dot com, I can now safely say that my version of Bitcoin core does not seem to be seeing these inscription transactions while they're in the mempool but only after they are confirmed by the miners.  That being the case, if you're like me and you don't want to perpetuate these inscriptions, you might just want to downgrade to core v. 20.2 as it certainly seems to be filtering out these inscriptions from nodes mempools.  Also, if I'm not mistaking, this likely explains the reason for the differences between my nodes mempool sizes and transactions as from the mempool dot space and blockstream dot info as they are likely running the very latest versions of bitcoin core and therefore propagating these transactions.  Merry Christmas everyone and may everyone have a happy (no ordinals or inscriptions) New Year!   

[BitcoinCanSaveUsAll]

Update:

My node is not seeing any taproot transactions whatsoever and as per mempool dot space, all the inscriptions transactions that it's seeing is in fact taproot.  That said, it's clear
that running v. 20.2 is eliminating the ordinals spam + any taproot traffic from the mempool.

[o_e_l_e_o]

We discussed this back on the first page of this thread. Taproot support was first added in 0.21.0, so if you are running 0.20.x then you will ignore all taproot transactions.

If you wish to filter ordinal transactions, there are other ways to do this without running software which is several years out of date.

[DaveF]

Update:

My node is not seeing any taproot transactions whatsoever and as per mempool dot space, all the inscriptions transactions that it's seeing is in fact taproot.  That said, it's clear
that running v. 20.2 is eliminating the ordinals spam + any taproot traffic from the mempool.

No, it will eliminate them from YOUR mempool. It's going to do absolutely nothing for the mempool in general.
And since mining pools (with one exception) and miners are trying to make as much BTC as possible they are going to want those TXs and will be running software that will allow them to get them.

All you are doing is running old outdated software with other potential vulnerabilities that does not support newer features.

-Dave

[BitcoinCanSaveUsAll]

I'm now noting that my nodes running core V 20.2 now shows over 1 gigabyte in each of their local mempools while mempool dot space shows 1.74 Gigs.  That should mean I'm seeing the majority of the mempool dot spaces mempool however this should not be possible as also according to mempool dot space more than 50% of the current mempool is taproot transactions, none of which can be seen by my nodes.  Something seems amiss here. It should also be noted that among my nodes the discrepancy in memory usage and TX count continues amongst them unabated since Taproot's introduction.